tjmga
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Post by tjmga on Jul 28, 2020 12:46:40 GMT -5
I am working up a load for my 24V 222 Rem over 20 ga. The 222 has a 1:14 twist. I started by purchasing 50 gr. PPU factory ammo. These shot well with a velocity of 3005 f/s. I purchased some Hornady 50 gr SXSP #2245 bullets to reload. I worked up from 24.0 gr CFE223 in .5 gr steps. At 25.0 everything was good and I was getting 2990 f/s,at 25.5 the velocity jumped to 3100 f/s and the bullets were key-holing. At 26.0 the velocity was 3140 f/s and key-holing. I would be happy with 3000 f/s if this is where it wants to be. The question is why would the bullet key hole at the higher velocity? Has this been seen by anyone else? It seem strange that the velocity would jump 100+ f/s at 25.5 gr, all other steps were about 35 f/s.
Thanks in advance for any help.
tj
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Post by painter on Jul 28, 2020 15:21:06 GMT -5
Normally, increased velocity reduces keyholing, or under stabilization, of a bullet in barrels with marginal twist rates.
I've never seen this before.
It would be interesting to see what happens with lighter bullets.
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tjmga
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Post by tjmga on Jul 29, 2020 17:21:33 GMT -5
Painter That is the same thought I have. I even checked the Miller equation to see if I had my thoughts reversed. All loads were shot on the same day. Hopefully someone will chime in with an answer. If not I will take my question elsewhere. Thanks for your reply. tj
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Post by painter on Jul 30, 2020 7:48:20 GMT -5
I went to the Hornady site, and they tout those bullets performance at low velocity.
I'm thinking the flat base design is the issue with increased velocity.
I'm thinking you just need to load them at < 3000 fps.
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Post by vancmike on Aug 3, 2020 12:57:52 GMT -5
Hmm. It is a puzzle. "Classic" most accurate speed for a .222 Rem/50 gr. is around 3150+/- fps. At least that's what several of my reloading manuals say, including an older Hornady manual. That older manual has various recipes for pushing that bullet to 3100 fps, but no faster.
Newer Hornady manuals recommend no faster than 3000 fps, with several powders showing maximum pressures at 2900 fps. Pressure guns, as used in firearms labs, are all bolt actions. Your O/U, being a break-action has a lower pressure tolerance (OK, let's admit it: it's a weaker action), but I honestly don't know if a .222 can stress a Model 24's action all that much. In any case, what will 3100fps do, with that bullet, that 2990fps won't?
One last thought: have you checked the rifle barrel's crown? It's possible, though improbable, that a tiny nick would throw off a bullet at higher speeds, while not affecting one at lower velocities.
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Post by cas on Aug 9, 2020 9:45:21 GMT -5
All reloading manuals get slower with time. lol
Is their speed limitations a pressure issue, or a bullet construction concern? Hmmm.. I wonder.
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tjmga
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Post by tjmga on Aug 10, 2020 12:53:19 GMT -5
Thanks everyone for your replies. I am going to limit my velocity to 3000 f/s with that bullet. I have checked the crown and it looks really good. I don't have an issue not exceeding the 3000 f/s mark, it's just that what is happening is the opposite of what I would expect. tj
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Post by vancmike on Aug 10, 2020 12:54:41 GMT -5
All reloading manuals get slower with time. lol Is their speed limitations a pressure issue, or a bullet construction concern? Hmmm.. I wonder. I've read part of the reason is the change from cup to psi. The other part, they say: lawyers. But I'll go back to my premise that neither a critter nor a paper target will notice a 150 fps drop in velocity of a 50 gr. bullet.
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